Barber says that the suggested use of copper sulfate (crystal blue) has serious issues with toxicity and control. He doesn't support its use either. What Barber advises is the use of hot water, borax and alcohol.
His suggestion is to use a solution of hot water (five gallons) with two cups of borax laundry booster. Stir this until the borax is dissolved and then add one pint of isopropyl "rubbing" alcohol.
"A person could run this solution through a pressure washer very easily and there is no need to worry about toxicity or what it will do to nearby plants and building materials," Barber said. "The benefits are that you don't have to rinse and the residual borax left behind is a potent fungicide that will not harm pets or children. Some people have mentioned smelling the alcohol, but this is necessary as an antiseptic and drying agent. The alcohol smell should dissipate quickly, especially when outdoors."
Barber may be reached at (417) 862-9284.